1. Human Peripheral Blood Primary Cells Peripheral blood cells are the cellular components of blood, consisting of erythrocytes, leucocytes and platelets, which are found within the circulating pool of blood. A peripheral blood mononuclear cell (PBMC) is any peripheral blood cell having a round nucleus, including lymphocytes (T cells, B cells, NK cells) and monocytes. Peripheral blood cells offered by Creative Bioarray are extracted from whole blood using ficoll and gradient centrifugation, which will separate the blood into a top layer of plasma, followed by a layer of PBMCs and a bottom fraction of polymorphonuclear cells and erythrocytes. Since there are plenty of unknown problems on immunology, culturing and researching the peripheral blood cells in vitro can serve the purpose.